Nitroesters, i.e., nitrates of polyvalent aliphatic or cyclic alcohols are used in the treatment of coronary artery disease, i.e., in the extended treatment of angina pectoris, the prevention of attacks, and post-infarction therapy.
Common forms of application are oral and especially transdermal, the latter form permitting a direct and systemic action on the vascular system through the skin acting as a reservoir and controlling membrane, as well as a uniform sustained release of the nitroesters.
Whereas spray preparations are intended mainly for the treatment of acute attacks, unguent preparations, e.g., ointments on the basis of oil-water emulsions and gel preparations, produce a prolonged action due to the nature of the vehicle and also a controlled release of the active nitroester substances.
Especially thixotropic gels formed with skin-penetrating oils on the one hand contain the oil as the vehicle for carrying the active substance through the skin, and on the other hand, by means of the thixotropic agent and any other desired carrier substances, they produce a uniform release of the active substance from the gel to or within the surface of the skin.
The present invention relates to gel preparations of nitroesters having an action on the coronary arteries.
It is known to prepare nitroesters of the kind which will be described in detail below by dissolving them in oils, such as fatty oils, with disperse silica, for example, in the form of gels of a spreadable consistency, whose viscosity is only slightly dependent on temperature.
However, if the gels are let stand for a long time in packaging such as capsules, ointment containers or tubes, a disadvantage is found in the segregation of the liquid oil, which interferes with the use of the gels and impairs the uniform release of the active substances. Also, the separated oil can leak out of the package.
The problem therefore existed of reliably preventing the separation of oils from gel preparations containing the active agents, i.e., of preventing so-called "oiling out."